The heart is frequently involved in the acquired immunodeficiency syndrome (AIDS). This study was planned to assess the prevalence of cardiac involvement in a large and selected population of patients who died of AIDS. Of 440 AIDS patients who underwent autopsy, cardiac involvement was documented in 82 patients. Dilated cardiomyopathy was found in 12 patients; lymphocytic interstitial myocarditis was documented in 30 patients, and in 10 of 12 patients with dilated cardiomyopathy. Inflammatory infiltrate was predominantly composed by CD3+ and CD8+ with a positive staining for major histocompatibility class I in 70% of the cases. Infective endocarditis was documented in 28 patients, pericardial effusion in 53 patients, myocardial Kaposi's sarcoma in 2 patients, myocardial B-cell immunoblastic lymphoma in 1 patient. Sequences of human immunodeficiency virus (HIV) nucleic acid were detected using the technique of in situ hybridization in the myocytes of 29 autopsy patients and in 25 of 29 patients with a positive hybridization signal an active myocarditis was documented. Among them, 7 presented a coinfection with Coxsakievirus group B, 2 with Epstein-Barr virus, and 1 with cytomegalovirus. HIV-associated cardiomyopathy may be related either to a direct action of HIV on the myocardial tissue or to an autoimmune process induced by HIV even in association with other cardiotropic viruses.